First-in-Human Study of Mutant-selective PI3Kα Inhibitor, RLY-2608, as a Single Agent in Patients With Advanced Solid Tumors and in Combination With Endocrine Therapy +/- a CDK4/6 or CDK4 Inhibitor in Patients With Advanced Solid Tumors or Advanced Breast Cancer

Study Summary

This is an open-label, FIH study designed to evaluate the maximum tolerated dose, recommended Phase 2 dose, safety, tolerability, PK, pharmacodynamics, and preliminary antineoplastic activity of RLY-2608, in advanced solid tumor patients with a Phosphatidylinositol-4,5-bisphosphate-3 kinase, catalytic subunit alpha (PIK3CA) mutation in blood and/or tumor per local assessment. The study will evaluate RLY-2608 as a single agent for patients with unresectable or metastatic solid tumors. It will also evaluate RLY-2608 in combination RLY-2608 + fulvestrant and in triple combination RLY-2608 + fulvestrant + CDK4/6 inhibitor (palbociclib or ribociclib) or CDK4 inhibitor (PF-07220060) for patients with HR+ HER2- locally advanced or metastatic breast cancer. The RLY-2608 single agent arm, RLY-2608 + fulvestrant combination arm, and triple combination arms will have 2 parts: a dose escalation (Part 1) and a dose expansion (Part 2).

Conditions

PIK3CA Mutation Solid Tumor, Adult HER2-negative Breast Cancer Breast Cancer Metastatic Breast Cancer Advanced Breast Cancer Unresectable Solid Tumor

Interventions / Drugs

RLY-2608 Fulvestrant Palbociclib 125mg Ribociclib 400mg Ribociclib 600mg PF-07220060 100mg PF-07220060 300 mg

View on ClinicalTrials.gov ↗

Sponsor

Study Details

Enrollment930 participants

Primary Completion—

Lead SponsorRelay Therapeutics, Inc.

Data Retrieved2026-04-11 04:26:00.986218+00:00

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